allow configuration of GatewayPorts

[pwyliu]

This is a small PR to allow configuration of the sshd GatewayPorts directive. This is useful for hosts that act as a bastion host, where clients are proxying local server ports though it and want to expose on a non loopback address.

[rndmh3ro]

Thanks for this!

Can you add ssh_gateway_ports: true here: https://github.com/dev-sec/ansible-ssh-hardening/blob/master/default.yml#L22, so it gets tested in travis?

[rndmh3ro]

Thank you. :)

[pwyliu]

Awesome, thanks for merging! 👏👍🙌🙆